• 한국결정성장학회지
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• 제8권4호
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• pp.573-580
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• 1998

MgO와 Al 분말을 자전고온연소합성법으로 $MgAl_2O_4$ 스피넬 상을 합성하였다. MgO 와 Al을 테르밋 반응으로 생성하였으며, 가열반응생성으로 $800^{\circ}C$ 예열온도에서 반응시켰다. DTA/TG, 합성생성물, 최고온도 공정조건에 대해 연구하였고, MgO와 Al은 MgO+2Al+ 3/$2O_3$ $\rightarrow$ $MgAl_2O_4$ 로 합성되었다. 미반응된 재료로부터 MgAl2O4 스피넬의 활성화 에너지는 -264.8kcal/mol의 발생열량과 5634K의 최고 반응온도로 계산되었다. 테르밋 반응후의 시험편의 체적느 6% 증가하였다.

• 한국작물학회지
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• 제38권4호
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• pp.330-335
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• 1993

참깨품종의 온도와 일장에 따른 항산화성분 함률차이를 조사하여 참깨 재배기술개선에 필요한 기초자료를 얻고자 무분지형 단백깨와 수원깨 및 분지형 안산깨와 한섬깨를 공시하여 작물시험장 인공기상실에서 온도와 일장을 달리 처리하여 시험하였던 바 얻어진 결과를 요약하면 다음과 같다. 1. 일장과 온도처리에 따른 참깨 항산화함량의 품종간 차이가 있었다. 2. 온도의 차이에 따라 20/15$^{\circ}C(주간온도/연간온도)에서 sesamin 0.22%, sesamolin 0.16% 인데 비하여 30/25$^{\circ}C에서는 sesamin 0.28%, sesamolin 0.19%를 보여 저온조건 보다는 고온조건에서 항산화 성분함량이 높았다. 3. 일장의 차이에 따라 11시간 일장에서 sesamin 0.24%, sesamin 0.26%, sesamolin 0.20%와 큰 차이가 없었다. 4. 따라서 참깨 항산화성분 함량은 일장의 길이보다는 온도의 차이에 의해 크게 영향 받는 것으로 생각된다.

• 한국세라믹학회지
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• 제28권10호
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• pp.803-809
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• 1991

Microstructure, room temperature resistivity and temperature coefficient of resistance of BaTiO3 ceramics were characterized and measured in this study. The basic composition of the BaTiO3 cremics was formed by adding 0.25 mol% Dy2O3 and 0.07 mol% MnO2 to the BaTiO3 composition. Samples of the BaTiO3 ceramics were prepared by adding various amounts of the TiO2, SiO2 and Al2O3 to the basic composition. An addition of 1 mol% TiO2, 2 mol% SiO2 and 0.5 mol% Al2O3 to the basic composition resulted both the values of the room temperature resistivity and the temperatured coefficient being maxium. Meanwhile, an addition of 1 mol% TiO2 and 1 mol% Al2O3 to the basic composition resulted the value of the room temperature resistivity maxium and the temperature coefficient minimum. The temperature coefficient showed a maximum value as well as a minimum value when the three kinds of the additives were added together to the basic composition of the BaTiO3 ceramics. Maxed phases of BaTi3O7, BaTiSiO5 and BaAl2Si2O8 were present at the grain boundary.

• 한국대기환경학회지
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• 제7권1호
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• pp.31-40
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• 1991

This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.113-115
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• 2001

In order to design the power appratus such ac bus bar, the current carrying ampacity should be determined, Since it is limited by maxium operating temperature, it is very important to predict temperature-rise on it. The main causes to raise temperature are joule's loss in the current carrying conductor and induced circulating and eddy current in the tank. The heat transfer is divided into convection and radiation on boundary, determining convection heat transfer coefficient is not easy. This paper propose a new technique that can be used to estimate the temperature rise in the extra high voltage bus bar. The heat transfer coefficient is analytically calculated by applying Nusselt Number depending on temperature as well as model geometry. The analytic method which use heat transfer coefficient is coupled with finite element method. The temperature distribution in the bus bar by the proposed method shows good agreement with experimental data.

• 대한지리학회지
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• 제35권4호
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• pp.519-528
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• 2000

본 연구에서는 지난 20세기 동안 한반도 중부 지방의 여름철 7월과 8월의 일최고기온과 일최저기온의 지역적 패턴을 조사하였다. 조사결과 연구기간 동안 여름철 일최고기온의 평균 및 일정 임계치 이상의 고온 특이일의 빈도가 감소하는 경향을 나타냈다. 반면, 여름철 일최저기온의 평균은 지속적으로 상승하여 결과적으로 이 지역의 여름철 일교차의 평균이 급격히 감소하는 경향을 보였다. 일최고기온의 감소 추세는 1950년대 이래로 진행되어온 조림사업으로 인한 삼림 임목 축적량의 증가와 관련성이 있는 것으로 추정되었다. 이 밖에도 본 연구에서는 현재의 도시화 지구온난화가 지속된다는 가정 하에 기온극값 발생빈도와 장기적인 패턴변화를 예측하는 모델을 제시하였다.

• 동아시아식생활학회지
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• 제6권3호
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• pp.317-323
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• 1996

Physicochemical characteristics of Cassia tora seeds roasted at different conditions were investigated. Intact Cassia tora seeds were composed of water 11.6% crude protein 13.1%, crude fat 4.4%, curde fiber 13.8%, N-free extract 47.2% and ash 4.9%. Stacking volume ratio was increased generally by swelling, but soluble solids were decreased by rosating process L and B values decreased conspicuously as roasting temperature increase, but $\Delta$E value increased. The content of anthraquinones was 1, 200mg% in unroasted Cassia tora seeds, it increased as roasting time and temperature increase and reached maxium amount at 19$0^{\circ}C$-30min, 21$0^{\circ}C$-20min. and 23$0^{\circ}C$-10min. agter that it decreased remarkably. Optimum roasting condition of Cassia tora seeds was 21$0^{\circ}C$-20min.

• 한국식생활문화학회지
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• 제12권5호
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• pp.469-475
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• 1997

The modification of rice powder was attempted by treatment of acetic acid and epichlorohydrin to improve the functional properties of baby food. The initial gelatinization temperature of rice powder determined by amylograph was decreased from $79.5^{\circ}C$ to $63^{\circ}C$ by modification. The apparent and maxium viscosity of rice paste at $95^{\circ}C$ before and after modification were increased from 92B.U. to 236B.U. and from 100B.U. to 202B.U., respectively. The light transmittance of modified rice paste was increased from the temperature of $60^{\circ}C$ and by increasing the degree of substitution at the fixed temperature, while decrease more or less by the treatment of epichlorohydrin. The degree of retrogradation of the paste was decreased from 28.7 to 18.0 upon modification. The rate of syneresis of modified rice powder was decreased with increasing the drgree of substitution and ,the extend of epichlorohydrin treatment. Syneresis was not observed when acetylated rice powder whose DS value is 0.048 was treated with 0.25% of epichlorohydrin for the formation of cross-linkage. The addition of modified rice powder in preparation of semi-solid type infant food could improve the quality without lowering overall digestibility.

• E2M - 전기 전자와 첨단 소재
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• 제9권8호
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• pp.836-850
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• 1996

In this study, we have analyzed structural analysis and measured ferroelectric characteristics of PZT thin films prepared by sol gel process with different sintering conditions and different Zr/Ti mot%. When the Zr mot% of PZT thin film was increased, it was found that the remanent. polarization and coercive field were decreased and increased, respectively. Also, the maxium dielectric constant of PZT(50/50) thin film was 786.8. We got double hysteresis(anti-fcrroelectric) curve from PbZrO$_{3}$ thin film. As heating rate goes up, pyrochlore phase of PZT thin film was decreased and dielectric and ferroelectric characteristics were improved. As a result of variation of sintering temperature and time 500.deg. C-800.deg. C and 5 sec.-8 hours, respectively, we got optimal sintering temperature and time. The optimium sintering temperature and time of conventional furnace method and rapid thermal processing method were 650.deg. C-700.deg. C for 30-60 minutes and 700.deg. C/20 seconds-2 minutes, respectively.

• 한국기후변화학회지
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• 제6권4호
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• pp.277-281
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• 2015

A Chinese cabbage is one of important vegetables which accounts for more than 60 percent of leaf vegetable. However, cultivation area and yield of Chinese cabbage are steadily decreasing recently. Because meteorological changes destabilize the balance of Chinese cabbage, we need to study on meteorological factors affecting estimation of Chinese cabbage yield. So we conducted a panel analysis using mean temperature, maximum temperature, minimum temperature, precipitation and sunshine's duration from August to November for estimation of Chinese cabbage yield. As the results, we found that if the mean temperature of September increase by $1^{\circ}C$ the amount of production of Chinese cabbage per unit area was increased by 348.6 kg/10a. We also found that the mean temperature of October increased by 174.8 kg/10a, that of November 148 kg/10a, the difference between the maxium temperature and the minimum temperature of October equals 443.3 kg/10a. However, we found that the difference between the maximum temperature and the minimum temperature of November decreased 274.1 kg/10a.